1. Field of the Invention
The present invention relates to mixed solvent compositions used as cleaning agents for electronic components including a printed circuit board and an IC, precision machinery parts, of glass substrates, for example.
Abbreviations and terms used in the present specification are illustrated below.
R113: 1,1,2-trichloro-1,2,2-trifluoroethane PA0 R225; a mixture of one or two or more of dichloropentafluoropropane having the molecular formula C.sub.3 HCl.sub.2 F.sub.5 PA0 R225ca: 3,3-dichloro-1,1,1,2,2-pentafluoropropane PA0 R225cb: 1,3-dichloro-1,1,2,2,3-pentafluoropropane PA0 R225mix: a mixture of at least two dichloropentafluoropropane isomers selected from the group consisting of R225ca, R225cb and other dichloropentafluoropropane isomers PA0 R43-10mee: 1,1,1,2,3,4,4,5,5,5-decafluoropentane R51-14M: a mixture of one or two or more of perfluorohexane having the molecular formula C.sub.6 F.sub.14 PA0 R51-14: perfluoro (n-hexane) PA0 R51-14my: perfluoro (4-methylpentane) PA0 R51-14mcy: pefluoro (3-methylpentane) PA0 R51-14mix: a mixture of at least two perfluorohexane isomers selected from the group consisting of R51-14, R51-14my, R51-14mcy and other perfluorohexane isomers PA0 Azeotropic mixed solvent composition: a mixed solvent composition, the composition of which does not substantially vary even by repeating distillation-condensation operations PA0 Azeotropic-like mixed solvent composition: a mixed solvent composition, the composition of which varies only within the range of .+-.2% even by repeating distillation-condensation operations
2. Description of the Background
To remove various oils, greases, or fluxes for example, R113 which is nonflammable, low toxic and excellent in stability, or a mixed solvent composition comprising R113 and a solvent miscible with R113 is widely used. Since R113 has such characteristics that it does not have an adverse effect on a base material such as a metal, a plastic or an elastomer and selectively dissolves various soils, it has been suitable for cleaning various electronic components, precision machinery parts, or components for example, made of a metal, a plastic, or an elastomer for example. Also, U.S. Pat. No. 5,304,322 discloses a cleaning agent for aircrafts, which comprises a C.sub.4 -C.sub.8 perfluorocarbon, a C.sub.2 -C.sub.5 hydrochlorofluorocarbon and a C.sub.5 -C.sub.9 petroleum distillate. In spite of various advantages of conventionally used R113, its production and consumption are regulated, because it has such a long life time in the troposphere by virtue of its chemical stability that it can diffuse to the stratosphere, where it is decomposed by an ultraviolet ray, producing chlorine radicals and the chlorine radicals cause a chain reaction with stratospheric ozone to deplete the ozone layer.
For this reason, alternative solvents to R113, which do not cause depletion of the ozone layer are widely being researched.
An object of the present invention is to provide a novel mixed solvent composition which satisfies the excellent properties of conventional R113 and can be used as an alternative solvent which does not substantially affect the ozone layer.